1,721,303 research outputs found
Transcatheter aortic valve implantation in lower-risk patients: what is the perspective?
No full textIn the last decade, transcatheter aortic valve implantation (TAVI), a disruptive technology, has revolutionized the therapy of symptomatic severe aortic stenosis, and current guidelines state that the recommendations for TAVI and surgical aortic valve replacement (SAVR) are equivalent in patients at high-risk. Increased operator experience, technical advances in the new generation of transcatheter heart valves (THV) and excellent TAVI results in recently published randomized controlled trials have led to the expansion of TAVI indication as an alternative to SAVR in intermediate-risk subjects, given appropriate patient selection. The time is opportune to examine the role of TAVI in low-risk patients, currently the objective of on-going randomized trials. This review aims to summarize the available knowledge on TAVI in low- to intermediate-risk patients and to discuss the potential advantages and pitfalls TAVI will face in this clinical setting
Reappraisal of Ischemic Heart Disease: Fundamental Role of Coronary Microvascular Dysfunction in the Pathogenesis of Angina Pectoris
Full text linkIn recent years, it has become apparent that coronary microvascular dysfunction plays a pivotal pathogenic role in angina pectoris. Functional and structural mechanisms can affect the physiological function of the coronary microvasculature and lead to myocardial ischemia in people without coronary atheromatous disease and also in individuals with obstructive coronary artery disease. Abnormal dilatory responses of the coronary microvessels, coronary microvascular spasm, and extravascular compressive forces have been identified as pathogenic mechanisms in both chronic and acute forms of ischemic heart disease. The condition characterized by anginal symptoms and evidence of myocardial ischemia triggered by coronary microvascular dysfunction, in the absence of obstructive coronary disease, is known as microvascular angina. The concept of microvascular angina, however, may extend further to include patients with obstructive coronary artery disease and individuals with angina after coronary revascularization or heart transplantation because coronary microvascular dysfunction contributes to myocardial ischemia in many such patients. Patients with microvascular angina constitute a sizeable proportion of all cases of stable angina undergoing diagnostic coronary angiography and of those with persisting angina after successful coronary revascularization. Coronary microvascular dysfunction is also often responsible for angina in individuals with cardiomyopathy and heart valve disease as well as acute coronary syndrome cases such as Takotsubo syndrome and myocardial infarction with no obstructive coronary artery disease. Patients with stable microvascular angina present typically with effort or rest chest pain and a reduced coronary flow reserve or microvascular spasm. This condition, which affects women and men, can markedly impair quality of life and prognosis and represents a substantial cost burden to healthcare systems and individuals alike. In recent years, progress in the diagnosis of myocardial ischemia and the use of tests to investigate functional and structural causes for a reduced coronary flow reserve and microvascular spasm have allowed the identification of an increased number of cases of microvascular angina in everyday clinical practice. Although some of the available anti-anginal drugs may be helpful, treatment of coronary microvascular dysfunction remains a major challenge. The present article discusses the fundamental role that coronary microvascular dysfunction plays in the pathogenesis of ischemic heart disease, the clinical characteristics of patients presenting with microvascular angina, and possible diagnostic and therapeutic strategies
Impact of atrial fibrillation on outcomes of patients treated by transcatheter aortic valve implantation: A systematic review and meta-analysis
No full textBACKGROUND:
Conflicting data have been reported related to the impact of atrial fibrillation (AF) on the outcomes after transcatheter aortic valve implantation (TAVI). We aimed to assess the prognosis of TAVI-treated patients according to the presence of pre-existing or new-onset AF.
METHODS:
Studies published between April 2002 and November 2016 and reporting outcomes of pre-existing AF, new-onset AF, or sinus rhythm in patients undergoing TAVI were identified with an electronic search. Pairwise and network meta-analysis were performed. Outcomes of interest were short- and long-term mortality, stroke, and major bleeding.
RESULTS:
Eleven studies (11,033 individuals) were eligible. Compared to sinus rhythm, short-term and long-term mortality were significantly higher in new-onset AF (short-term OR 2.9, P=.002; long-term OR 2.3, P<.0001) and pre-existing AF groups (short-term OR 2.7, P=.004; long-term OR 2.8, P<.0001). Compared to sinus rhythm, new-onset AF increased the risk of stroke at early (OR 2.1, P<.0001) and late follow-up (OR 1.92, P<.0001), and the risk of early bleedings (OR 1.65, P=.002), while pre-existing AF increased the risk of late stroke (OR 1.3, P=0.03), but not the risk of bleeding. Compared to pre-existing AF, new-onset AF correlated with higher risk of early stroke (OR 1.7, P=.002) and major bleedings (OR 1.7, P=.002).
CONCLUSIONS:
AF is associated with impaired outcomes after TAVI, including mortality, stroke and (limited to new-onset AF) major bleedings. Compared to pre-existing AF, new-onset AF correlates with higher risk of early stroke and major bleedings. Improved management of AF in the TAVI setting, including tailored antithrombotic treatment strategies, remains a relevant need
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Changes in Management Following Detection of Previously Unknown Atrial Fibrillation by an Insertable Cardiac Monitor (from the REVEAL AF Study)
No full text- …
